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Blow forming apparatus for producing double-walled vessels

  • US 3,932,104 A
  • Filed: 04/29/1974
  • Issued: 01/13/1976
  • Est. Priority Date: 04/29/1974
  • Status: Expired due to Term
First Claim
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1. An apparatus for blow forming of hollow bodies so as to produce a double-walled vessel, the combination comprising:

  • a mold including a pair of mated halves having an open cavity defined by the shape of opposing internal wall surfaces;

    sleeve means disposed over said open cavity for separating supplied parison within said mold cavity into coaxial inner and outer tubes;

    means forming a portion of said mold at its extreme opposite ends for joining the opposite ends of said coaxial inner and outer tubes to seal said circular space between said inner and outer tubes so as to constitute the double walls of said vessel;

    an extrusion die for extruding the parison into said cavity;

    said sleeve comprising a part of said die whereby parison is divided into a pair of downwardly depending coaxial tubes into said mold cavity;

    said joining means comprises cut-off portions at opposite ends of said mold cavity for severing said parisons and engaging the terminating ends of said tubes together in an integral joint;

    means for trapping air between the opposing surfaces of said inner and outer tubes comprising;

    air means for introducing pressurized air into the center of said coaxial tubular parisons urging the parisons into the form of said cavity.

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